This invention relates to localization of radio frequency sources. The invention also relates to a virtual touchscreen application for a radio frequency localization system.
Localization of Radio Frequency (RF) sources is an active area of research interest. The majority of RF source localization systems focus on the problem of discovering an exact location of an RF source.
Referring to FIG. 1, one example of such a localization system 100 includes two pairs of antennas, a first antenna pair 102 and a second antenna pair 104, and generally uses a triangulation approach. For each pair of antennas 102, 104, the individual antennas of the pair have a spacing which is less than or equal to λ/2 (where λ is the wavelength). This constraint on the antenna spacing ensures that each of the antenna pairs 102, 104 forms only a single lobe in the antenna sensitivity pattern.
In the system 100 of FIG. 1, the antenna pairs 102, 104 are positioned such that a first lobe 106 formed by the first antenna pair 102 can be formed in a unique direction relative to a second lobe 108 formed by the second antenna pair 104. As an RF source 110 moves through an area in proximity to the antenna pairs 102, 104, the antenna pairs 102 sweep their respective lobes 106, 108 to track the location of the RF source 110.
The resolution of the location of the RF source 110 determined by the system 100 is dependent on a width of the lobes 106, 108. In particular, the location of the RF source 110 is only known to be within the area 112 where the two lobes 106, 108 intersect. In general, the location of the RF source 110 can be resolved to a location with a resolution in the tens of centimeters by the system 100. A standard approach for improving the location resolution of a system such as the system of FIG. 1 is to increase the number of antennas used in the system.